This invention relates to a graft/stent system for use in human or animal surgery.
One example of a type of graft/stent similar to the one discussed in this document is disclosed in EP 0326426A, which describes an artificial blood vessel in the form of a tubular sheath having a ring-like member located at each of its two ends.
Another example, disclosed in EP 0461791A, is an aortic graft with one of its tubular ends divided into two branches.
WO 99/37242 (USSN 09/036,588), the contents of which are incorporated herein by reference, discloses a reinforced graft formed from a flexible sheet of graft material to which is sewn a reinforcing wire. The graft/stent may be formed flat, then rolled into a tube and secured. The reinforcing wire is preferably sewn to the sheet in a ladder of substantially straight portions connected by substantially U-shaped connection portions.
To give the reader a basic understanding of some of the advantageous features of the invention, following is a brief summary of preferred versions of the graft/stent. As this is merely a summary, it should be understood that more details regarding the preferred versions may be found in the Detailed Description set forth elsewhere in this document. The claims set forth at the end of this document then define the various versions of the invention in which exclusive rights are secured.
In one preferred version of the invention, a tubular sheath defines a graft/stent. A flexible integral branch tube is also provided, with an end fixed to the tubular sheath at an opening in a side wall of the tubular sheath. The branch tube is a graft/stent along its entire length, and can be fully inverted along its entire length so as to be fully housed within the tubular sheath during an insertion operation in a human or animal body, and redeployed as a branch within the body after the insertion operation. The tubular sheath and/or the branch tube are preferably graft/stents as disclosed in WO 99/37242.
Preferably, the tubular sheath and/or the branch tube has filamentary reinforcing material (such as nitinol wire) attached thereto to provide support within the body. In a particularly preferred embodiment, the reinforcing material constitutes up to 10% of the diameter of the tubular sheath or the branch tube, with an amount of around 1% being particularly preferred. The bend diameter of the reinforcing material is preferably up to 10% (and most preferably about 5%) of the diameter of the tubular sheath or the branch tube. These parameters of the reinforcing material allow the branch tube to evert within the tubular sheath.
The tubular sheath preferably has at intervals along its length a plurality of rigidizing ring-like support members attached to the sheath around their respective circumferences and which are made of a shape memory material, so that when the members change shape, the sheath adopts a new cross-section in conformity with them along its whole length. This arrangement defines a compliant tubular sheath into which a series of open rings are integrated, wherein the rings act as rigidizing members and are capable of being radially compressed by mechanical forces in the martensitic phase so as to reduce the diameter, and which may returning in the austenitic phase to a memorized, larger diameter by a thermal effect.
The invention also relates to a tubular sheath having a branch tube which is sufficiently flexible to be inverted so as to be housed within the sheath during an insertion operation in a human or animal body, and to be redeployed as a branch after the operation. The sheath and/or the branch tube may employ annular support members (preferably rigidizing members) of a shape memory material, as explained above. In all cases, the members may be discontinuous, e.g. a ring with a break so as to facilitate compression and re-expansion.